PEGylation

PEGylation (often styled pegylation) is the process of both covalent and non-covalent attachment or amalgamation of polyethylene glycol (PEG, in pharmacy called macrogol) polymer chains to molecules and macrostructures, such as a drug, therapeutic protein or vesicle, which is then described as PEGylated (pegylated). PEGylation is routinely achieved by incubation of a reactive derivative of PEG with the target molecule. The covalent attachment of PEG to a drug or therapeutic protein can "mask" the agent from the host's immune system (reduced immunogenicity and antigenicity), and increase the hydrodynamic size (size in solution) of the agent which prolongs its circulatory time by reducing renal clearance. PEGylation can also provide water solubility to hydrophobic drugs and proteins.

Around 1970, Frank F. Davis, a professor of biochemistry at Rutgers University, became interested in developing a process to render usable bioactive proteins of potential medical value. After considerable study, he concluded that the attachment of an inert and hydrophilic polymer might extend blood life and control immunogenicity of the proteins. Polyethylene glycol was chosen as the polymer. A team of Davis, Theodorus Van Es and Nicholas C. Palczuk conducted animal studies and found that PEG attachment greatly extended blood life and controlled immunogenicity of the proteins. A patent application was filed in 1973 and patent issued in 1979. The inventors and Abraham Abuchowski conducted extensive additional PEGylation studies on various enzymes. In 1981 Davis and Abuchowski founded Enzon, Inc., which brought three PEGylated drugs to market. Abuchowski later founded and is CEO of Prolong Pharmaceuticals.

PEGylation is the process of attaching the strands of the polymer PEG to molecules, most typically peptides, proteins, and antibody fragments, that can improve the safety and efficiency of many therapeutics. It produces alterations in the physiochemical properties including changes in conformation, electrostatic binding, hydrophobicity etc. These physical and chemical changes increase systemic retention of the therapeutic agent. Also, it can influence the binding affinity of the therapeutic moiety to the cell receptors and can alter the absorption and distribution patterns.

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